Description (Is for C++)

The purpose of this challenge is to write a basic class with member functions and variables. This challenge illustrates the use of various functions and constructors.

Requirements

1. Note that, typically, writing cout statements in classes are a bad idea. This exercise does employ the use of cout statements within the class to illustrate how the functions are being used and called.
2. Create a class called Engine
3. In Engine, create the following private properties:
   1. int rpm, speed
   2. int drive_mode, rpm_gain, max_speed
   3. string drive_modes[4]
   4. string filename
4. Write a private function set_drive_modes(). In this function, simply fill the array drive_modes with the values Eco Pro, Comfort, Sport, Sport Plus. Make sure you do not redeclare/recreate a new drive_modes array in this function. The values of 0, 1, 2, 3 will be assigned later to drive_mode and will respectively represent the string values in the drive_modes array.
5. Write a constructor that takes in a single string parameter. Remember that constructors have the same name as the class, do not have a return type and must be public. Set the private variable filename to the string parameter of the constructor.
6. Write a private function int load_drive_mode(). This function will open a file whose filename is stored in the filename private variable. In this file, you expect to read a single integer value. Read this value and return it out of the function. If the file doesnt exist, return a value of 1.
7. Write a private function void save_drive_mode(). This function will save the value of the private variable drive_mode into a file whose name is stored in filename. Also, when saving drive_mode, include a line terminator (endl) to ensure that this token can be read later.
8. Write a private function prep_engine(). This function will set the values of rpm_gain and max_speed based on the value of drive_mode as below:
   1. When drive_mode is 0, set rpm_gain to 100, set max_speed to 65
   2. When drive_mode is 1, set rpm_gain to 300, set max_speed to 85
   3. When drive_mode is 2, set rpm_gain to 1000, set max_speed to 185
   4. When drive_mode is 3, set rpm_gain to 1500, set max_speed to 185
9. In your constructor, add the following functionality
   1. call set_drive_modes() function
   2. set drive_mode to the value returned by calling load_drive_mode().
   3. call prep_engine() function
   4. set rpm to 0
   5. set speed to 0
10. Write a public function void accelerate(). This function, every time its called will increase rpm by rpm_gain and speed by 10. speed cannot exceed max_speed.
11. Write a public function void decelerate(). This function, every time its called will decrease rpm by 200 and speed by 10. speed cannot go below 0 and rpm cannot go below 0.
12. Write a public function void increase_drive_mode(). This function will increment the value of drive_mode by 1, not to exceed 3. This function will call prep_engine() and save_drive_mode() after the adjustment of drive_mode.
13. Write a public function void lower_drive_mode(). This function will decrement the value of drive_mode by 1, not to go below 0. This function will call prep_engine() and save_drive_mode() after the adjustment of drive_mode.
14. Write a public function void show_status(). This function will display the status of drive_mode, rpm and speed
15. Finally, in main(), write out the main below which will essentially use the class and its functions.

Sample main()

 int main() { Engine engine("bmwx3"); char action; do { cout << "A - accelerate "; cout << "D - decelerate "; cout << "M - increase drive mode "; cout << "N - lower drive mode "; cout << "Q - park the car (quit) "; cout << "Action? "; cin >> action; if (action == 'a') engine.accelerate(); else if (action == 'd') engine.decelerate(); else if (action == 'm') engine.increase_drive_mode(); else if (action == 'n') engine.lower_drive_mode(); engine.show_status(); } while (action != 'q'); return 0; } 

Sample Interaction

 A - accelerate D - decelerate M - increase drive mode N - lower drive mode Q - park the car (quit) Action? m Dashboard: Drive Mode: Sport, Speed: 0, RPM: 0 A - accelerate D - decelerate M - increase drive mode N - lower drive mode Q - park the car (quit) Action? a Dashboard: Drive Mode: Sport, Speed: 10, RPM: 1000 A - accelerate D - decelerate M - increase drive mode N - lower drive mode Q - park the car (quit) Action? a Dashboard: Drive Mode: Comfort, Speed: 20, RPM: 1300 A - accelerate D - decelerate M - increase drive mode N - lower drive mode Q - park the car (quit) Action? a Dashboard: Drive Mode: Comfort, Speed: 30, RPM: 1800 A - accelerate D - decelerate M - increase drive mode N - lower drive mode Q - park the car (quit) Action? a Dashboard: Drive Mode: Comfort, Speed: 40, RPM: 2100 >> run it a few times pressing various choices to ensure that drivem modes change and speeds do not exceed the max rated speed for the various drive modes